The present invention relates generally to wireless transmission systems, and relates more particularly to a wireless video transmission system.
Developing enhanced television systems is a significant consideration for consumer electronics manufacturers. In conventional television systems, a display device may be utilized to view program information received from a program source. The conventional display device is typically positioned in a stationary location because of restrictions imposed by various physical connections coupling the display device to input devices, output devices, and operating power. Other considerations such as display size and display weight may also significantly restrict viewer mobility in traditional television systems.
Portable television displays may advantageously provide viewers with additional flexibility when choosing an appropriate viewing location. For example, in a home environment, a portable television may readily be relocated to view programming at various remote locations throughout the home. A user may thus flexibly view television programming, even while performing other tasks in locations that are remote from a stationary display device.
Furthermore, a significant proliferation in the number of potential program sources (both analog and digital) may benefit a system user by providing an abundance of program material for selective viewing. In particular, an economical wireless audio/video transmission system for flexible home use may enable television viewers to significantly improve their television-viewing experience by facilitating portability while simultaneously providing an increased number of program source selections.
The evolution of digital data network technology and wireless digital transmission techniques may provide additional flexibility and increased quality to television systems in the home. However, current wireless data networks typically are not optimized for transmission of high quality video information.
High quality continuous media streams, such as video image streams, in their raw form often require high transmission rates, or bandwidth, for effective and/or timely transmission. In many cases, the cost and/or effort of providing the required transmission rate is prohibitive. This transmission rate problem is often solved by compression schemes that take advantage of the continuity in content to create highly packed data. Compression methods such as based on Motion Picture Experts Group (MPEG) standards and its variants for audio and video are well known. With high resolution video, such as the resolution of 1080i used in high definition television (HDTV), the data transmission rate of such a video image stream will be very high even after compression.
One problem posed by such a high data transmission rate is data storage. Recording or saving high rate video streams for any reasonable length of time requires considerably large amounts of storage that can be prohibitively expensive. Another problem presented by high resolution video data is that many output devices are incapable of rendering the data. For example, display systems that can be used to view video image streams having a lower resolution may not be capable of displaying such a high resolution. Yet another problem is the transmission of continuous media in networks with a limited bandwidth or capacity. For example, in a local area network with multiple receiving/output devices, such a network will often have a limited bandwidth or capacity, and hence be physically and/or logistically incapable of simultaneously supporting multiple receiving/output devices. Furthermore, the available bandwidth of wireless interconnections and networks often varies over time and is unpredictable due to several factors.
Transmission of compressed media data over such networks is difficult, because a high bandwidth is required continuously, and because of the stringent delay constraints associated with continuous media streams. Degradation of the channel condition may result in data packets being lost or delayed, leading to distortions or interruptions of the media presentation.